Engine Oil- should it be black when fresh?

roswell

Its diesel, I have had my oil changed a good few times and everytime its black, i spoke to a friend who was a taxi driver at the time he advised me as he had had diesels for the last 20 odd years that the oil is always black once the car has been strarted

mistry_2

I looked at the oil on a tissue, and it did look a lot cleaner. So I think I was worring for no reason. Thanks for your replies.

Still not sure why a diesel would be different, but this seems to be the consent.

I spoke to friend who also mentioned an engine flush, apparently a garage he uses does this for £10 when you service your car with them.

missile

CAM belt failure can cause serious damage and cost a lot of money. You say log book marked as changed. Do you KNOW it was changed?

anewman

missile wrote: »

CAM belt failure can cause serious damage and cost a lot of money. You say log book marked as changed. Do you KNOW it was changed?

AFAIK it's normally a difficult job, costs a bit and in most vehicles is difficult for the non-technically minded to get to and check.

mistry_2

Yes it was changed, cause I had it changed

onejontwo

The engine oil in a diesel engine tends to be blacker than a petrol engine is because it operates with a far higher combustion pressure, that's why all diesel mechanics are always dirtier than petrol mechanics!!:D

navig8r

Some of the exhaust gasses are always present in the vehicle sump as a result of "blow by" and therefore in contact with the oil, the more the engine wears the more of the gasses escape resulting in blackening the oil at a faster rate , these gasses are sucked out and reburned to clean them of any oil they have picked up and to reduce sump pressure.Rub the inside of the exhaust tail pipe on petrol and diesel car ,tissue not finger,you will then see why the engine oil is blacker in the latter.
Dave